Rare artifacts will be unveiled this month in a new exhibit documenting the culture and contributions of California's first people at the California Museum in Sacramento. A huge stuffed condor from the Smithsonian, Modoc chief Captain Jack's buckskin jacket and a cape and arrowhead that belonged to Ishi, reputedly the last Native American to live a primitive life in California, will be showcased in "California Indians: Making A Difference," which opens March 31. "We have some objects that have never been on exhibit before," said curator P. Christiaan Klieger, an anthropologist affiliated with the California Academy of Sciences in San Francisco. "It's not your typical sort of basket exhib